config.yaml

#@ load("@ytt:data", "data")
---
foo: #@ data.values

schema.yaml

#@data/values-schema
#@overlay/match-child-defaults missing_ok=True
---
service:
  #@schema/validation min_len=1
  something: ""

schema2.yaml

#@data/values-schema
#@overlay/match-child-defaults missing_ok=True
---
echos:
- name: ""
  port: 8080
  text: "Hello #ytt World on 8080!"
service:
  enabled: true